isc-dhcp/common/dispatch.c

/* socket.c

   BSD socket interface code... */

/*
 * Copyright (c) 1995, 1996 The Internet Software Consortium.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of The Internet Software Consortium nor the names
 *    of its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This software has been written for the Internet Software Consortium
 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
 * Enterprises.  To learn more about the Internet Software Consortium,
 * see ``http://www.vix.com/isc''.  To learn more about Vixie
 * Enterprises, see ``http://www.vix.com''.
 */

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
#endif /* not lint */

#include "dhcpd.h"
#include <sys/ioctl.h>

struct interface_info *interfaces;
static struct hardware_link *interface_links;

static void got_one PROTO ((struct interface_info *));

/* Use the SIOCGIFCONF ioctl to get a list of all the attached interfaces.
   For each interface that's of type INET and not the loopback interface,
   register that interface with the network I/O software, figure out what
   subnet it's on, and add it to the list of interfaces. */

void discover_interfaces ()
{
	struct interface_info *tmp;
	struct interface_info *last;
	static char buf [8192];
	struct ifconf ic;
	int i;
	int sock;
	int address_count = 0;
	int ifix = 0;
	struct hardware_link *lp;
	struct subnet *subnet;
	struct shared_network *share;
	struct sockaddr_in *foo;
#ifdef USE_FALLBACK
	static struct shared_network fallback_network;
#endif

	/* Create an unbound datagram socket to do the SIOCGIFADDR ioctl on. */
	if ((sock = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
		error ("Can't create addrlist socket");

	/* Get the interface configuration information... */
	ic.ifc_len = sizeof buf;
	ic.ifc_ifcu.ifcu_buf = (caddr_t)buf;
	i = ioctl(sock, SIOCGIFCONF, &ic);
	close (sock);
	if (i < 0)
		error ("ioctl: SIOCGIFCONF: %m");

	/* Cycle through the list of interfaces looking for IP addresses.
	   Go through twice; once to count the number if addresses, and a
	   second time to copy them into an array of addresses. */
	for (i = 0; i < ic.ifc_len;) {
		struct ifreq *ifp = (struct ifreq *)((caddr_t)ic.ifc_req + i);
#ifdef HAVE_SA_LEN
		i += (sizeof ifp -> ifr_name) + ifp -> ifr_addr.sa_len;
#else
		i += sizeof *ifp;
#endif

		/* See if we've seen an interface that matches this one. */
		for (tmp = interfaces; tmp; tmp = tmp -> next)
			if (!strcmp (tmp -> name, ifp -> ifr_name))
				break;

		/* If there isn't already an interface by this name,
		   allocate one. */
		if (!tmp) {
			tmp = ((struct interface_info *)
			       dmalloc (sizeof *tmp, "get_interface_list"));
			if (!tmp)
				error ("Insufficient memory to %s %s",
				       "record interface", ifp -> ifr_name);
			memset (tmp, 0, sizeof *tmp);
			strcpy (tmp -> name, ifp -> ifr_name);
			tmp -> next = interfaces;
			interfaces = tmp;
		}

		/* If we have the capability, extract link information
		   and record it in a linked list. */
#ifdef AF_LINK
		if (ifp -> ifr_addr.sa_family == AF_LINK) {
			struct sockaddr_dl *foo = ((struct sockaddr_dl *)
						   (&ifp -> ifr_addr));
			tmp -> hw_address.hlen = foo -> sdl_alen;
			tmp -> hw_address.htype = ARPHRD_ETHER; /* XXX */
			memcpy (tmp -> hw_address.haddr,
				LLADDR (foo), foo -> sdl_alen);
		} else
#endif /* AF_LINK */

		if (ifp -> ifr_addr.sa_family == AF_INET) {
			struct iaddr addr;

			/* Get a pointer to the address... */
			foo = (struct sockaddr_in *)(&ifp -> ifr_addr);

			/* We don't want the loopback interface. */
			if (foo -> sin_addr.s_addr == htonl (INADDR_LOOPBACK))
				continue;

			/* If this is the first real IP address we've
			   found, keep a pointer to ifreq structure in
			   which we found it. */
			if (!tmp -> tif)
				tmp -> tif = ifp;

			/* Grab the address... */
			addr.len = 4;
			memcpy (addr.iabuf, &foo -> sin_addr.s_addr,
				addr.len);

			/* If this address matches the server identifier,
			   make a note of it. */
			if (addr_eq (addr, server_identifier))
				server_identifier_matched = 1;

			/* If there's a registered subnet for this address,
			   connect it together... */
			if ((subnet = find_subnet (addr))) {
				/* If this interface has multiple aliases
				   on the same subnet, ignore all but the
				   first we encounter. */
				if (!subnet -> interface) {
					subnet -> interface = tmp;
					subnet -> interface_address = addr;
				} else if (subnet -> interface != tmp) {
					warn ("Multiple %s %s: %s %s", 
					      "interfaces match the",
					      "same subnet",
					      subnet -> interface -> name,
					      tmp -> name);
				}
				share = subnet -> shared_network;
				if (tmp -> shared_network &&
				    tmp -> shared_network != share) {
					warn ("Interface %s matches %s",
					      tmp -> name,
					      "multiple shared networks");
				} else {
					tmp -> shared_network = share;
				}

				if (!share -> interface) {
					share -> interface = tmp;
				} else if (share -> interface != tmp) {
					warn ("Multiple %s %s: %s %s", 
					      "interfaces match the",
					      "same shared network",
					      share -> interface -> name,
					      tmp -> name);
				}
			}
		}
	}

	/* Weed out the interfaces that did not have IP addresses. */
	last = (struct interface_info *)0;
	for (tmp = interfaces; tmp; tmp = tmp -> next) {
		if (!tmp -> tif) {
			if (!last)
				interfaces = interfaces -> next;
			else
				last -> next = tmp -> next;
			continue;
		}

		foo = (struct sockaddr_in *)(&tmp -> tif -> ifr_addr);

		/* Find subnets that don't have valid interface
		   addresses... */
		for (subnet = (tmp -> shared_network
			       ? tmp -> shared_network -> subnets
			       : (struct subnet *)0);
		     subnet; subnet = subnet -> next_sibling) {
			if (!subnet -> interface_address.len) {
				warn ("subnet %s attached to interface %s %s",
				      piaddr (subnet -> net), tmp -> name,
				      "but has no alias on that network.");
				/* Set the interface address for this subnet
				   to the first address we found. */
				subnet -> interface_address.len = 4;
				memcpy (subnet -> interface_address.iabuf,
					&foo -> sin_addr.s_addr, 4);
			}
		}

		/* If a server identifier wasn't specified, take it
		   from the first IP address we see... */
		if (!server_identifier.len) {
			if (address_count > 1)
				warn ("no server identifier specified.");
			server_identifier.len = 4;
			memcpy (server_identifier.iabuf,
				&foo -> sin_addr.s_addr, 4);
			/* Flag the server identifier as having matched,
			   so we don't generate a spurious warning. */
			server_identifier_matched = 1;
		}
			

		/* Register the interface... */
		if_register_receive (tmp, tmp -> tif);
		if_register_send (tmp, tmp -> tif);

		tmp -> tif = (struct ifreq *)0; /* Can't keep this. */
	}
	if (!server_identifier_matched)
		warn ("no interface address matches server identifier");

#ifdef USE_FALLBACK
	strcpy (fallback_interface.name, "fallback");	
	fallback_interface.shared_network = &fallback_network;
	fallback_network.name = "fallback-net";
	if_register_fallback (&fallback_interface, (struct ifreq *)0);
#endif
}

#ifdef USE_POLL
/* Wait for packets to come in using poll().  Anyway, when a packet
   comes in, call receive_packet to receive the packet and possibly
   strip hardware addressing information from it, and then call
   do_packet to try to do something with it. 

   As you can see by comparing this with the code that uses select(),
   below, this is gratuitously complex.  Quelle surprise, eh?  This is
   SysV we're talking about, after all, and even in the 90's, it
   wouldn't do for SysV to make networking *easy*, would it?  Rant,
   rant... */

void dispatch ()
{
	struct interface_info *l;
	int nfds = 0;
	struct pollfd *fds;
	int count;
	int i;

	nfds = 0;
	for (l = interfaces; l; l = l -> next) {
		++nfds;
	}
	fds = (struct pollfd *)malloc (nfds * sizeof (struct pollfd));
	if (!fds)
		error ("Can't allocate poll structures.");

	i = 0;
	for (l = interfaces; l; l = l -> next) {
		fds [i].fd = l -> rfdesc;
		fds [i].events = POLLIN;
		fds [i].revents = 0;
		++i;
	}

	do {
		/* Wait for a packet or a timeout... XXX */
		count = poll (fds, nfds, (struct timeval *)-1);

		/* Get the current time... */
		GET_TIME (&cur_time);

		/* Not likely to be transitory... */
		if (count < 0)
			error ("poll: %m");

		i = 0;
		for (l = interfaces; l; l = l -> next) {
			if (!(fds [i].revents & POLLIN))
				continue;
			fds [i].revents = 0;
			got_one (l);
		}
	} while (1);
}
#else
/* Wait for packets to come in using select().   When one does, call
   receive_packet to receive the packet and possibly strip hardware
   addressing information from it, and then call do_packet to try to
   do something with it. */

void dispatch ()
{
	struct sockaddr_in from;
	struct hardware hfrom;
	struct iaddr ifrom;
	fd_set r, w, x;
	struct interface_info *l;
	int max = 0;
	int count;
	int result;
	static unsigned char packbuf [4095]; /* Packet input buffer.
						Must be as large as largest
						possible MTU. */

	FD_ZERO (&r);
	FD_ZERO (&w);
	FD_ZERO (&x);

	do {
		/* Set up the read mask. */
		for (l = interfaces; l; l = l -> next) {
			FD_SET (l -> rfdesc, &r);
			FD_SET (l -> rfdesc, &x);
			if (l -> rfdesc > max)
				max = l -> rfdesc;
		}

		/* Wait for a packet or a timeout... XXX */
		count = select (max + 1, &r, &w, &x, (struct timeval *)0);

		/* Get the current time... */
		GET_TIME (&cur_time);

		/* Not likely to be transitory... */
		if (count < 0)
			error ("select: %m");

		for (l = interfaces; l; l = l -> next) {
			if (!FD_ISSET (l -> rfdesc, &r))
				continue;
			got_one (l);
		}
	} while (1);
}
#endif /* USE_POLL */

static void got_one (l)
	struct interface_info *l;
{
	struct sockaddr_in from;
	struct hardware hfrom;
	struct iaddr ifrom;
	int result;
	static unsigned char packbuf [4095]; /* Packet input buffer.
						Must be as large as largest
						possible MTU. */

	if ((result = receive_packet (l, packbuf, sizeof packbuf,
				      &from, &hfrom)) < 0) {
		warn ("receive_packet failed on %s: %m", l -> name);
		return;
	}
	if (result == 0)
		return;

	ifrom.len = 4;
	memcpy (ifrom.iabuf, &from.sin_addr, ifrom.len);
	
	do_packet (l, packbuf, result,
		   from.sin_port, ifrom, &hfrom);
}